1. Field of the Invention
This invention relates generally to counterbalanced viewing apparatus boom suspension systems, and more particularly relates to a spring counterbalanced cantilever arm suspension system for remote stereoscopic CRT monitors for three dimensional computer or camera generated simulation environments.
2. Description of Related Art
Visual presentations of environments for computer or camera generated simulations are useful in many fields, such as three dimensional biomedical modeling of patient anatomy before surgery, architecture, flight training experiences, and wind tunnel behavior of aircraft structures, for example. This type of visual presentation can be particularly useful if presented stereoscopically, with CRT or LCD viewing devices providing binocular views from slightly different angles to allow the perception of depth in the views presented. Such viewing devices increase the illusion of presence in the scenes presented, and have therefore generally been referred to as providing a visual virtual environment, and more popularly as "virtual reality".
Head mounted stereoscopic viewers with sensors to give the visual virtual environment system feedback as to the orientation of viewing have been developed to allow the user to control the angle of view and appearance of movement through the projected visual environment by movement of the head mounted viewer. While some have been developed as helmets to be worn on the head, the weight of a unit including binocular CRT screens can be uncomfortable, if not suspended or at least partially supported. Such supported stereoscopic viewing devices are typically suspended by an articulated, counterbalanced boom having sensors at the joints of the boom and the viewing device to generate data concerning the position and orientation of the viewing device.
While counterbalancing the viewing device can remove the burden of carrying the full weight of the viewing device from the user, the total mass of the system is increased. In systems where the head mounted viewing device is provided in the form of a helmet or is strapped to the head of the user, the problem of overcoming the inertia of the viewing system can also make the system difficult to use. Helmet type viewing devices also are not easily left in a desired position and angle of view while a user attends to some other task, making it difficult for a user to look away to a control panel or keyboard. It has been found that it is useful to provide a free standing, fully suspended and counterbalanced stereoscopic viewer which can be used simply like a pair of binoculars which can be left in a desired position and angular orientation, and from which the user can easily look away to have ready access to a control system, such as a keyboard and computer monitor, for controlling various modes of operation of the visual virtual environment system. In such freely suspended viewing systems, due to the weight of the viewing device and the counterweights employed, moving the viewing device for a change of position or angle of view can produce a momentum in the suspension system and viewing device which can tend to carry the device beyond the position or angle desired, so that it would be desirable to reduce the overall inertia of the suspension system.
A conventional counterweighted boom suspension system also typically has a limited range of pivoting motion, since the counterweight on the boom can interfere with movement of the boom to a vertical position. Movement of such a conventional viewing device from a position on one side of the vertical line from the support base to an opposite side can typically be accomplished by a 180 degree rotation of the boom and realignment of the viewing device. It would therefore be desirable to provide a counterbalanced boom suspension system with an improved range of motion which would allow for fully counterbalanced movement of the viewing device to a raised vertical position and to opposing lowered horizontal positions. The present invention meets these needs.